Currently, uvulopalatopharyngoplasty (UPPP) is the most common surgical procedure used for the treatment of obstructive sleep apnea. Patients with clinically significant obstructive sleep apnea in whom medical treatment has failed or who are unwilling to comply with medical therapy are considered candidates for UPPP. The initial surgical results obtained in nonselected patients with obstructive sleep apnea were highly variable, approximately half of the patients experiencing more than a 50% reduction in the frequency of disordered breathing events postoperatively. Although differences in surgical technique likely account for some of the variability, preoperative differences in the site (or sites) of upper airway collapse are also thought to influence the surgical results. Because UPPP involves resection of the uvula, distal margin of the soft palate, palatine tonsils, and any excessive lateral pharyngeal tissue, patients with anatomic narrowing and collapse confined to the velopharyngeal or retropalatal region of the upper airway are considered optimal surgical candidates. Fiberoptic pharyngoscopy, cephalometric roentgenography, computed tomography, and somnofluoroscopy are procedures that can be used preoperatively to help select optimal candidates for UPPP. The results suggest that the success rate of UPPP can approach 66% with careful preoperative selection of patients.